1. Field of the Invention
This invention relates to a liquid crystal shutter panel applied to a display and a printer head and its manufacturing method and an optical printer head using the liquid crystal shutter panel.
2. Description of the Related Art
FIG. 7 shows a sectional view of a general structure of a liquid crystal shutter panel according to the related art, mounted with a drive IC (Integrated Circuit). In the liquid crystal panel, a common electrode 3a made of ITO (Indium Tin Oxide) coated with an upper orientation film 2a and a pixel electrode 3b made of ITO coated with a lower orientation film 2b are formed on facing inner surfaces of an upper glass board 1a and a lower glass board 1b. Liquid crystal 5 is sealed in a cell formed by bonding the upper glass board 1a and the lower glass board 1b by a seal material 4.
A blocking mask 6 for blocking light to an area except a display pixel is formed on the common electrode 3a formed on the upper glass board 1a. In the lower glass board 1b, a lower board frame part 1c projects toward one side. On the lower board frame part 1c, a wiring pattern 3c made of the ITO for connecting the pixel electrode 3b and the common electrode 3a and metal electrode coatings 7a and 7b for lowering an electrode resistance value of the wiring pattern 3c are formed. A drive IC 8 for driving the liquid crystal and a cable 9 for delivering a signal from an outside are joined on the metal electrode coating 7b. 
As illustrated in FIG. 8, the upper glass board 1a and the lower glass board 1b are formed on a sheet of a glass base board 10 in the stated liquid crystal shutter panel (a1). The upper orientation film 2a and a lower orientation film 2b are formed on the glass base board 10, and two sheets of glass base boards 10 are bonded by the seal material 4(b1). Then, by separating each of boards, a plurality of liquid crystal shutter panels is formed from two sheets of glass base boards 10(c1).
Generally, chromium metal which highly blocks light is used as a material for the blocking mask 6, and the blocking mask 6 is often formed together with the metal electrode coating 7a. However, a resistance value of the chromium metal is high, and the chromium metal is easily oxidized. Therefore, as illustrated in FIG. 7, a noble metal, e.g., gold, platinum, etc. which has high electrical conductivity and low corrosivity is used as the metal electrode coating 7b on the metal electrode coating 7a made of chromium.
Next, with reference to FIGS. 9 and 10, a method for forming the blocking mask 6 and an electrode pattern of the stated liquid crystal shutter panel is explained.
At first, an ITO electrode film 11 is formed on a whole surface of the glass base board 10 using a vapor-deposition method, sputtering method, etc. (step a0). Next, a metal chromium film 12 is formed on a whole upper surface of the ITO electrode film 11 using the vapor-deposition method, sputtering method, etc. (step b0). Then, a metal film 13 made of the gold or the platinum is formed on a whole upper surface of the metal chromium film 12 using the vapor-deposition method, sputtering method, etc. (step c0).
Next, steps for patterning the metal film 13 using a photo lithography method is explained. A photoresist film 14 of positive type is spin-coated on a whole upper surface of the metal film 13 (step d0). Next, a photomask 15 of positive type in which a wiring pattern image for drive IC is formed is placed to cover the photoresist film 14, and the photoresist film 14 is irradiated with ultraviolet rays 16 through the photomask 15. A wiring pattern of the photomask 15 is not transparent, and rest of the photomask 15 is transparent. A portion on the photoresist film 14, which has been exposed to the ultraviolet rays 16 through the photomask 15 becomes dissolvable in a developer, and removed (step e0). Next, the glass base board after processing the photoresist film 14 is soaked in an etchant for metal, and a portion of the metal film 13 exposed to a surface is etched (step f0). The photoresist film 14 remaining on the surface of the metal film 13 is stripped (step g0).
Next, like the above method, a photoresist film 14a of positive type is spin-coated on the whole surface of the glass base board 10 (step h0). Then, a photomask 15a in which a wiring pattern and a blocking mask shape are formed is placed on the glass base board 10 by positioning to match with the wiring pattern which was formed earlier, and the photoresist film 14 is irradiated with the ultraviolet rays 16 through the photomask 15a. A portion of the photoresist film 14a irradiated with the ultraviolet rays 16 through the photomask 15a becomes dissolvable in the developer, and removed (FIG. 10, step i0). Next, the glass base board 10 is soaked in the etchant for chromium, and a portion of the metal chromium film 12 exposed to a surface is etched (step j0). The photoresist film 14a remaining on the surface of the glass base board 10 is stripped (step k0).
Next, like the above method, a photoresist film 14b of positive type is spin-coated on the whole surface of the glass base board 10 (step 10). Then, a photomask 15b in which an ITO wiring pattern is formed is placed to cover the glass base board 10 by positioning to match with the wiring pattern which was formed earlier, and the glass base board 10 is irradiated with the ultraviolet rays 16 through the photomask 15b. A portion of the photoresist film 14b irradiated with the ultraviolet rays 16 through the photomask 15b becomes dissolvable in the developer, and removed (step m0). Next, the glass base board 10 is soaked in the etchant for ITO, and a portion of the ITO electrode film 11 exposed to a surface is etched (step n0). The photoresist film 14b remaining on the surface of the glass base board 10 is stripped (step o0). After these steps, the common electrode 3a, the pixel electrode 3b, the wiring pattern 3c, the metal electrode coatings 7a and 7b and the blocking mask 6 are formed on the glass base board 10.
In a method for forming the blocking mask and the electrode pattern according to the related art, the metal film 13 is formed on the whole surface of the glass base board 10. Therefore, a large area of the metal film 13 which is unnecessary is removed, and the metal film 13 made of the gold, platinum, etc. which is expensive is wasted. Further, in the method for forming the blocking mask and the electrode pattern according to the related art, a number of steps in manufacturing increases, e.g., the photomask must be used three times, etc. Consequently, there is a problem that manufacturing costs become high.